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Hydrates of Ferric Chloride as Thermal Recording Compounds

IP.com Disclosure Number: IPCOM000097401D
Original Publication Date: 1962-Nov-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Damm, EP: AUTHOR

Abstract

Hydrates of ferric chloride can be used as thermal sensitive recording compounds. The mechanism of recording is: (1) The hydrolysis of these compounds occurs at elevated temperatures to produce localized acidic areas. (2) At the elevated temperatures, the acid produced causes premature charring of the cellulose.

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Hydrates of Ferric Chloride as Thermal Recording Compounds

Hydrates of ferric chloride can be used as thermal sensitive recording compounds. The mechanism of recording is:
(1) The hydrolysis of these compounds occurs at elevated

temperatures to produce localized acidic areas.
(2) At the elevated temperatures, the acid produced causes

premature charring of the cellulose.

When Fe Cl(3) 6 H(2)O is coated onto card stock and heated in selective areas, a color change from yellow to brown-black occurs in these areas. The color change is permanent and appears not to be affected by humidity conditions. This inertness to humidity rules out simple dehydration of the hydrated ferric chloride. The color conversion temperature is above 130 degrees centigrade.

A gelatin and ethyl cellulose combination serves as a good coating base for these compounds. The ethyl cellulose acts as an acid absorber which chars instead of the base document. This, in addition to the fact that the thermally sensitive compound is fixed on or near the surface of the document by the binder, serves to reduce document tendering.

As an alternative approach, the hydrated ferric chloride can be placed selectively on the paper by any printing technique and the entire document heated.

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